The Influence of the Curing Process on the Response of Textile Composites.

Curing;Textile Composites;Finite Elements;Nonlocal;Aerospace Engineering;Engineering;Aerospace Engineering

Heinrich, ChristianSundararaghavan, Veera ;

University of Michigan

关键词: Curing;    Textile Composites;    Finite Elements;    Nonlocal;    Aerospace Engineering;    Engineering;    Aerospace Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/84441/cheinric_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Textile composites are a promising engineering material that offer high specific strengthand fracture toughness. To allow for rapid development of new products and to allowfor virtual testing using numerical simulations, a thorough understanding of the materialstate and the material response to external load is necessary. In previous studies it hasbeen observed that the use of ;;virgin” matrix properties leads to numerical predictions ofcomposite behavior that is not in accord with experimental observations. It was concludedthat presence of fibers during the curing process of the epoxy alters the matrix materialproperties.To study these effects further, different physical effects are taken into consideration.First, the evolution of temperature and degree of cure is investigated through concurrentsolution of the heat conduction equation and an empirical curing law. The model is used toinvestigate the influence of curing parameters, geometry and thermal conductivity on thecuring time and maximum temperature in the epoxy.Next, a novel curing model for epoxy to describe the phase transition from liquid resinto solid epoxy has been developed. The curing of epoxy is treated as a continuous creationof non-interacting networks. The model accounts for an evolution of elastic properties ascure progresses and predicts resulting cure stresses. It has been shown that considerablestresses develop during the curing process in the epoxy inside the composite.To account for non-linear material behavior during cure and after applying loads, themodel has been augmented by a continuum damage mechanics formulation. Mesh objective results are obtained through a nonlocal formulation. Here the damage depends on the state of the material in a finite volume around the material point ofinterest. The combined curing and damage model has been applied to a woven composite unit cell and it is shown that cure at elevated temperatures and large chemical shrinkage can cause degradation of the epoxy material inside the composite prior to the application of external load. As a result, the onset of nonlinear effects occur at lower applied mechanical loads and the ultimate strength of thecomposite is significantly reduced.